Exoplanets

If we don't ask how long they last, but instead ask what's the probability that there have been any civilizations at all, now matter how long they lasted. I'm not asking whether they exist now or not, I'm just asking in general about probabilities to make a technological civilization anywhere and at any time in the history of the university. That, we're able to constrain. What we found was basically that there have been 10 billion trillion habitable zone planets in the universe. What that means is those are 10 billion trillion experiments that have been run. The only way that we're the only time that this whole process from abiogenesis to a civilization has occurred is if everyone one of those experiments failed. Therefore, you could put a probability, we called it the Pessimism Line. We don't really know what nature sets for the probability of making intelligent civilizations, but we could set a limit using this. We could say, look, if the probability per habitable zone planet is less than 10 to the minus-22, one in 10 billion trillion, then yeah, we're alone. If it's anywhere larger than that, then we're not the first. It's happened somewhere else. To me, that was mind-blowing. It doesn't tell me there's anybody nearby, the galaxy could be sterile. It just told me that unless nature's really has some bias against civilizations, we're not the first time this has happened. This has happened elsewhere over the course of cosmic history.

You wrote a book about aliens. The big question, how many alien civilizations are out there? Yeah, that's the question. The amazing thing is that, after two-and-a-half millennia of people yelling at each other, or setting each other on fire occasionally over the answer, we now actually have the capacity to answer that question. In the next 10, 20, 30 years, we're going to have data relevant to the answer to that question. We're going to have hard data finally that will, one way or the other ... Even if we don't find anything immediately, we will have gone through a number of planets. We'll be able to start putting limits on how common life is.

Yeah, I think we can. I think we're learning how to do that now. One part is trying to just figure out how planets form themselves in doing the simulations. That cascade from dust grains up to planetary embryos, that's hard to simulate because you got to do both the gas, and you got to do the dust and the dust colliding, and all that physics. Once you get up to a planet-sized body, then you have to switch over to almost a different kind of simulation. Often what you're doing is you're assuming the planet this this spherical ball, and then you're doing a 1D, a radial calculation. You're just asking, "All right, what is the structure of it going to be? Am I going to have a solid iron core, or am I going to get a solid iron core with a liquid iron core out around it?" Like we have on Earth. Then you get a silicate, rocky mantle, and then a crust. All those details, those are beyond being able to do full 3D simulations from Ab Initio, from scratch. We're not there yet.

I wonder if there is some extremely elevated levels of chaos, almost like catastrophes behind every leap of evolution. You're not going to have leaps. In human societies, we have an Einstein that comes up with a good idea. But it feels like on an evolutionary timescale, you need some real big drama going on for the evolutionary system to have to come up with a solution to that drama. An extra complex solution to that drama. Well, I'm not sure if that's true. I don't know if it needs to be an almost extinction event.

So really, on a scale of a planet when there's billions and trillions of organisms on a planet, they can actually have planetary scale impact. Yeah.

Now I wonder if the technosphere also has a Gaian feedback or elements of a Gaian feedback? Such that the technosphere will also fight to some degree for homeostasis. Open question, I guess. Well, I'm glad you asked that question. Because that paper that David, and Sara, and I wrote, what we were arguing was is that over the history of a planet ... When life first forms, 3.8 billion years ago, it's thin on the ground. You've got the first species, these are all microbes. There are not enough of them to exert any kind of these Gaian feedbacks. We call that an immature biosphere. But then as time goes on, as life becomes more robust and it begins to exert these feedbacks keeping the planet in the place where it needs to be for life, we call that a mature biosphere. I'm sure later on, we're going to talk about definitions of life and such. There's this great term called autopoiesis that Francisco Varela, the Neurobiologist Francisco Varela came up with. He said, "One of the defining things about life is this property of autopoiesis," which means self-creating and self-maintaining. Life does not create the conditions which will destroy itself. It's always trying to keep itself in a place where it can stay alive. The biosphere, from this Gaian perspective, has been autopoietic for billions of years.

Before we forget, I got to ask you about this paper. Right.

Speaking of simplifying everything down to an equation, let's return back to the question of how many alien civilizations are out there and talk about the Drake Equation. Yeah.

Habitable zone is an idea that was developed in the 1958 by the Chinese American astronomer, Xu Sheng, and it was a brilliant idea. It said, "Look, I can do the simple calculation. If I take a planet and just stick it at some distance from a star of what's the temperature of the planet? What's the temperature of the surface?" So now, give it a standard Earth-like atmosphere and ask, "Could there be liquid water on the surface?" We believe that liquid water is really important for life. There could be other things that's happening fine, but if you were to start off trying to make life, you'd probably choose water as your solvent for it. So basically, the habitable zone is the band of orbits around a star where you can have liquid water on the surface. You could take a glass of water, pour it on the surface, and it would just pull up. It wouldn't freeze immediately, which would happen if your planet is too far out and it wouldn't just boil away if your planet's too close in. So, that's the formal definition of the habitable zone. So, it's a nice strict definition, there's probably way more going on than that, but this is a place to start.

To me, it seems like there should be alien civilizations everywhere. Why the Fermi paradox? Why haven't we seen them? Okay, the Fermi paradox. I love talking about the Fermi paradox because there is no Fermi paradox. Dun dun, dun dun. Yeah, so the Fermi paradox, let's talk a about the Fermi paradox and the history of it. So, Enrico Fermi, it's 1950, he's walking with his friends at Los Alamos nuclear weapons lab to the Cantina, and there had been this cartoon in the New Yorker, they all read the New Yorker. And the cartoon was trying to explain why there had been this rash of garbage cans being disappearing in New York. And this cartoon said, "Oh, it's UFOs." Because it's 1950, the first big UFO craze happened in '47.

What phenomena emerge when a bunch of small things get together and interact? Going back to this paper, a new empirical constraint on the prevalence of technological species in the universe. This paper that expands on the Drake equation, what are some interesting things in this paper? Well, so the main thing we were trying to do with this paper is say, "Look, we have all of this exoplanet data." It's got to be good for something, especially since two of the terms that have been nailed down empirically are two terms in the Drake equation. So, F sub P, that's the second term, fraction of stars that have planets, and then N sub E, the average number of planets in the habitable zone. Those are the second and third term in the Drake equation. So, what that means is all the astronomical terms have been nailed. And so, we said, "Okay, how do we use this to do something with the Drake equation?"

Do you think if humans colonize Mars, the dynamic between the civilization on Earth and Mars will be fundamentally different than the dynamic between individual nations on Earth right now? That's a thing to load into the agent-based simulation we're talking about. Yeah. If we settle it, Mars will very quickly want to become its own nation.

So as we look out there, according to the Drake equations we just discussed, it seems impossible to me that there's not civilizations everywhere. So how do we look at them, this process of SETI? I have to put on my scientist hat and just say, my gut feeling is that dumb life, so to speak, is common. I can see ways in which intelligent civilizations may be sparse, but until... We got to go look, it's all armchair astronomy.

What about detecting maybe through direct imaging or in other ways, megastructures, that the civilizations build? You know what's great about megastructures is first of all, it's fun to say, who doesn't want to say megastructure? Alien, megastructure, right? Every morning, I'm looking for an opportunity to say that. So the err example of this is the Dyson sphere, which is amazing because it was literally 1960 that this idea came up.

Right. What is the Kardashev scale and where are humans on it?

So how do we detect alien type one, two, and three civilizations? So we've been kind of talking about basically type one civilization detection. Yeah. Right,

So, you think it's not possible to travel fast than the speed of light? I wouldn't say that. I wouldn't say that, but what I think, if you look at the physics, we understand, every possibility for faster than light travel really relies on something that doesn't exist. So, the cool thing is Einstein's field equations, you can actually play with them, the equations are right there. You can add things to the right or left-hand side that allow you to get something like the Alcubierre drive. That was a metric that showed you like, "Oh, it's a warped bubble." It's a warping of spacetime that moves through spacetime faster than the speed of light.

The generation ship too, which I talked about in the book, the idea of also you talked about the extending human lifetimes or the stasis, the cryostasis, which is a mainstay of science fiction that you can basically put in suspended animation and such. None of these things we know are possible. But what's so interesting, and this is why I love science fiction, the way it seeds ideas, all these ideas we're going to talk about because they've been staples of science fiction for 50 years. The whole field of cryogenics.

What do you think aliens look like? So, we talked about all the different kinds of bio signatures that might leave or techno signatures, but what would they look like when we show up? Are they going to have arms and legs? Are they going to be recognizable at all? Are they going to be carbon-based? Yeah. So, great question, and this question gets to the heart of thinking about life, about what life is. And this is the physical part of that, there's also the informational part of it. But let's just talk about the physical part of it, which is anything that we're going to call life is probably going to work on Darwinian evolution. That's the nice thing about Darwinian evolution, just like we know the laws of physics are general, the laws of Darwinian evolution are this logic, this basic logic that anything we'd reasonably call life probably has to operate under these kinds of principles.

If there's advanced civilizations out there, what do you think is the proper protocol for interacting with them? Do you think they would be peaceful? Do you think they would be warlike? What do we do next? We detect the civilizations through all the technosignatures we've been talking about, maybe direct imaging, maybe there's really strong signal. We come up with a strategy of how to actually get there. Yeah.

I am all in favor of an open, agnostic, transparent, scientific investigation of UFOs and UAPs. But the idea that there's any data that we have that links UFOs and UAPs to non-human technology, I just think the standards, none of what is claimed to be the data lives up to the standards of evidence. So, let's just take a moment on that idea of standards of evidence, because I made a big deal about this both in the book and elsewhere whenever I talk about this. So, what people have to understand about science is we are really, our scientists, we are really mean to each other, we are brutal to each other. Because we have this thing that we call standards of evidence, and it's the idea of you have a piece of evidence that you want to link to a claim. And under what conditions can you say, "Oh, look, I've got evidence of this claim X, Y, and Z." And in science, we are so mean to each other about whether or not that piece of evidence lives up to the standards that we have. And we spent 400 years determining what those standards are, and that is why cell phones work. If you didn't have super rigorous standards about what you think that's, "Oh, this little antenna, I've invented a new kind of antenna that I can slip into the cell phone and I can show you that it works."

Since you said it's the biggest question, which is an interesting thought experiment, what is the biggest scientific question we can possibly answer? Some people might say about what happened before the Big Bang, some big physics questions about the universe. I could see the argument for how many alien civilizations or if there's other life out there? You want to speak to that a little bit? Why is it the biggest question in... Why is it number one in your top five? I've evolved in this, right? I started off as a theoretical physicist. I went into computational astrophysics, magnetohydrodynamics of star formation, but I always was a philosophy minor. I always had these sort of bigger questions sort of floating around the back of my mind. And what I've come to now is the most important question for physics is, what is life? What the hell is the difference between a rock and a cell, fundamentally? And what I really mean by this, this is where I'm going to go non-traditional, is that really the fundamental question that is agency. What does it mean to be an autonomous agent? How the hell does that happen? I'm not a reductionist. I'm not somebody who's just like, well, you just put together enough chemicals and bing, bang, boom, and it suddenly appears there's something that really is going to demand a reconception of what nature itself is.

Yeah, time is really interesting one. Time is really important to us humans. What is time? Yeah, right. What is time? So the way we have tended to view it is we've taken, this is what, when Husserl talks about the surreptitious substitution, we've taken Einstein's beautiful, powerful, formal system for viewing time, and we substituted that for the actual experience of time. So the block universe, where next Tuesday is already written down in the block universe, the four dimensional universe, all events are already there. Which is very potent for making certain kinds of predictions within the scientific framework. But it is not lived time. And this was pointed out to Einstein, and he eventually recognized it. Very famous meeting between Henri Bergson, who was the most famous philosopher of the early 20th century and Einstein, where Einstein was giving a talk on relativity-

So going back to Kant and organism versus machine. So I showed you a couple of legged robots. Very cool.

What do you make of the fact that this individual observer, you as an individual observer only get a finite amount of time to exist in this world? Does it make you sad? No, actually it doesn't make me sad. Okay, so full reveal, I have been doing contemplative practice in the zen tradition for 30 years. I've been staring at a wall for 30 years, and it's taught me a lot. I really value what that practice has given me about the nature of experience. And one of the things it's taught me is I don't really matter that very much. This thing I call Adam Frank is really, it's kind of a construct. There's this process going on of which I am actually fundamentally, and that's super cool, but it's going to go. I don't know where it came from. It's going to go, I don't really need it to, and then who the hell knows? I'm not an advocate for an afterlife, but just that what I love, zen, has this idea of beyond birth and death, and they don't mean reincarnation. What they mean is, "Dude, you don't even really understand what life is." You know what I mean? I'm like this core level of your own experience. So your ideas about what death is are equally ill-formed.